Fuel supply assemblies are disclosed in EP 1.221.545 A2, DE 10345653 A1 and DE 102004009310 A1. In the fuel supply assembly disclosed in EP 1.221.545 A2, a carburettor is provided with a butterfly valve (throttle valve) with a butterfly (throttle disc). When turned to full throttle, the butterfly valve closes an aperture in the partition wall and thereby ensures that all fuel flows into the channel defined as a first channel, while substantially pure air flows through a second channel. In part throttle conditions, however, the aperture in the partition wall is partially open allowing most of the fuel to flow into the first channel. A portion, which apparently can be considerable, will also flow into the second channel, resulting in increased losses of fuel into an exhaust port of the engine.
The assembly disclosed in DE 10345653 A1 employs a carburettor of the same design as EP 1.221.545 A2, and it is specifically mentioned that the openings between the two channels, which are established when the butterfly has adopted a slightly opened position, promote an equalisation of the pressure in the air channel, i.e. in the second channel, when the two stroke engine operates with a low load.
Also, the assembly disclosed in DE 1002004009310 A1 employs a carburettor with a butterfly valve, which, in all positions except full load position will leave a passage-way through the partition wall on the downstream side as well as on the upstream side of the butterfly. The openings in the partition wall are much smaller than those of the two foregoing prior art disclosures, but they are still large enough to cause a considerable amount of fuel to escape from the first channel into the second channel, i.e. into the auxiliary air channel. In order to reduce this flow of fuel into the auxiliary air channel, and hence reduce the content of fuel in that channel, a baffle element is provided in the first channel, i.e. in the channel for conducting the air/fuel mixture. However, every element located in the first channel—the air/fuel mixture channel forms an obstacle for the flow of the air/fuel-mixture, and this is particularly a drawback when full gas is desired.